Phase Behavior of Phospholipid Bilayer Membranes under High Pressure.

High-pressure studies on the bilayer phase transitions of phosphatidylcholines containing linear saturated acyl chains are reviewed. Temperature-pressure phase diagrams of lipid bilayer membranes are shown; the pressure-induced, interdigitated gel phase is found in addition to liquid crystal, ripple gel and lamellar gel phases. The minimum pressure for the interdigitation of lipid bilayers decreases with an increase in acyl chain length in a non-linear manner. Thermodynamic quantities for phase transitions are also discussed.